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[PATCH v6 2/2] vhost-user: fix VirtQ notifier cleanup
From: |
Xueming Li |
Subject: |
[PATCH v6 2/2] vhost-user: fix VirtQ notifier cleanup |
Date: |
Mon, 1 Nov 2021 16:38:13 +0800 |
When vhost-user device cleanup is executed and un-mmaps notifier
address, VM cpu thread writing the notifier fails by accessing invalid
address error.
To avoid this concurrent issue, call RCU and wait for a memory flatview
update, then un-mmap notifiers in callback.
Fixes: 44866521bd6e ("vhost-user: support registering external host notifiers")
Cc: qemu-stable@nongnu.org
Cc: Yuwei Zhang <zhangyuwei.9149@bytedance.com>
Signed-off-by: Xueming Li <xuemingl@nvidia.com>
---
hw/virtio/vhost-user.c | 50 +++++++++++++++++++++-------------
include/hw/virtio/vhost-user.h | 2 ++
2 files changed, 33 insertions(+), 19 deletions(-)
diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index c671719e9b..5adad4d029 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -25,6 +25,7 @@
#include "migration/migration.h"
#include "migration/postcopy-ram.h"
#include "trace.h"
+#include "exec/ramblock.h"
#include <sys/ioctl.h>
#include <sys/socket.h>
@@ -1143,15 +1144,27 @@ static int vhost_user_set_vring_num(struct vhost_dev
*dev,
return vhost_set_vring(dev, VHOST_USER_SET_VRING_NUM, ring);
}
-static void vhost_user_host_notifier_remove(struct vhost_dev *dev,
- int queue_idx)
+static void vhost_user_host_notifier_free(VhostUserHostNotifier *n)
{
- struct vhost_user *u = dev->opaque;
- VhostUserHostNotifier *n = &u->user->notifier[queue_idx];
- VirtIODevice *vdev = dev->vdev;
+ assert(n && n->old_addr);
+ munmap(n->old_addr, qemu_real_host_page_size);
+ n->old_addr = NULL;
+}
+
+static void vhost_user_host_notifier_remove(VhostUserState *user,
+ VirtIODevice *vdev, int queue_idx)
+{
+ VhostUserHostNotifier *n = &user->notifier[queue_idx];
if (n->addr) {
- virtio_queue_set_host_notifier_mr(vdev, queue_idx, &n->mr, false);
+ if (vdev) {
+ virtio_queue_set_host_notifier_mr(vdev, queue_idx, &n->mr, false);
+ }
+ assert(n->addr);
+ assert(!n->old_addr);
+ n->old_addr = n->addr;
+ n->addr = NULL;
+ call_rcu(n, vhost_user_host_notifier_free, rcu);
}
}
@@ -1190,8 +1203,9 @@ static int vhost_user_get_vring_base(struct vhost_dev
*dev,
.payload.state = *ring,
.hdr.size = sizeof(msg.payload.state),
};
+ struct vhost_user *u = dev->opaque;
- vhost_user_host_notifier_remove(dev, ring->index);
+ vhost_user_host_notifier_remove(u->user, dev->vdev, ring->index);
if (vhost_user_write(dev, &msg, NULL, 0) < 0) {
return -1;
@@ -1486,12 +1500,7 @@ static int
vhost_user_slave_handle_vring_host_notifier(struct vhost_dev *dev,
n = &user->notifier[queue_idx];
- if (n->addr) {
- virtio_queue_set_host_notifier_mr(vdev, queue_idx, &n->mr, false);
- object_unparent(OBJECT(&n->mr));
- munmap(n->addr, page_size);
- n->addr = NULL;
- }
+ vhost_user_host_notifier_remove(user, vdev, queue_idx);
if (area->u64 & VHOST_USER_VRING_NOFD_MASK) {
return 0;
@@ -1510,9 +1519,12 @@ static int
vhost_user_slave_handle_vring_host_notifier(struct vhost_dev *dev,
name = g_strdup_printf("vhost-user/host-notifier@%p mmaps[%d]",
user, queue_idx);
- if (!n->mr.ram) /* Don't init again after suspend. */
+ if (!n->mr.ram) { /* Don't init again after suspend. */
memory_region_init_ram_device_ptr(&n->mr, OBJECT(vdev), name,
page_size, addr);
+ } else {
+ n->mr.ram_block->host = addr;
+ }
g_free(name);
if (virtio_queue_set_host_notifier_mr(vdev, queue_idx, &n->mr, true)) {
@@ -2460,17 +2472,17 @@ bool vhost_user_init(VhostUserState *user, CharBackend
*chr, Error **errp)
void vhost_user_cleanup(VhostUserState *user)
{
int i;
+ VhostUserHostNotifier *n;
if (!user->chr) {
return;
}
memory_region_transaction_begin();
for (i = 0; i < VIRTIO_QUEUE_MAX; i++) {
- if (user->notifier[i].addr) {
- object_unparent(OBJECT(&user->notifier[i].mr));
- munmap(user->notifier[i].addr, qemu_real_host_page_size);
- user->notifier[i].addr = NULL;
- }
+ n = &user->notifier[i];
+ assert(!n->addr);
+ vhost_user_host_notifier_remove(user, NULL, i);
+ object_unparent(OBJECT(&n->mr));
}
memory_region_transaction_commit();
user->chr = NULL;
diff --git a/include/hw/virtio/vhost-user.h b/include/hw/virtio/vhost-user.h
index f6012b2078..03aa22d450 100644
--- a/include/hw/virtio/vhost-user.h
+++ b/include/hw/virtio/vhost-user.h
@@ -12,8 +12,10 @@
#include "hw/virtio/virtio.h"
typedef struct VhostUserHostNotifier {
+ struct rcu_head rcu;
MemoryRegion mr;
void *addr;
+ void *old_addr;
} VhostUserHostNotifier;
typedef struct VhostUserState {
--
2.33.0